Police said that 122 opposition supporters have been imprisoned for up to six months since Saturday night, with more than 100 other activists detained amid sporadic violence nationwide.

"Special teams of magistrates working with police have sentenced them to up to six months in prison," police spokesman Masud Ahmed told AFP, adding there had been 87 on-the-spot convictions in Dhaka since the protests started.

Twenty-eight people were jailed in the country's southern port city of Chittagong and seven people in the north, including five in Sirajganj town, where the worst strike violence broke out.

"Police fired rubber bullets and tear gas to break up protestors and around a dozen people, including two policemen, were injured," said local police inspector Mostafa Harun.

At least nine buses and taxis were set ablaze by protestors and dozens of people were injured as small but violent protests broke out in cities across the country, police said.

More than 9,000 policemen and 3,000 Rapid Action Battalion (RAB) paramilitaries have been deployed in Dhaka, as the strike shut shops, businesses and schools and left major roads and highways deserted.

The main opposition Bangladesh Nationalist Party (BNP) and its main ally, Jamaat-e-Islami, called the strike to protest against recent changes to the electoral system, which they say unfairly favour the incumbent government.

Prime Minister Sheikh Hasina said last month that a decades-old election system, in which a neutral caretaker government takes over for three months to hold polls, would be scrapped.

Opposition leader Khaleda Zia has said her right-of-centre party will not contest any future polls if the caretaker system, which oversaw four successive elections, is abolished.

The system was introduced to guarantee free and fair polls in Bangladesh, which has a long tradition of political violence since independence in 1971.

Copyright AFP (Agence France-Presse), 2011